A computer that operates with numbers represented by directly measurable quantities (as voltages or rotations)--- compare digital computer, hybrid computer
Analog computer is a form of computer that uses the continuously changeable aspects of physical phenomena such as electrical, or hydraulic quantities to model the problem being so
lved. In contrast, digital computers represent varying quantities symbolically as their numerical values change.
The development of transistors made electronic analog computers practical, and until digital computers had developed sufficiently, theycontinued to be comomly used in science and industry.
Analog computers can have a very wide range of complexity slide rule and nomographs are the simplest , while naval gunfire control computers and large hybrid digital/analog computers were among the most complicated.